Intek 100CS - Manual (Page 8)

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SECTION 3 ! OPERATION
3.1 START UP
Typically, Rheotherm flow switches come from the factory set up for a 10 to 1 flow rate range, and with
the trip level set approximately as requested by the customer. The trip level can be adjusted using the
instructions in SECTION 3.3.
When power is first turned on, the flow switch may indicate a high flow rate, even if there is no flow
occurring. Correct indication of flow level will result after an initial period, which can extend to about
forty (40) seconds and depends on where the trip adjust is set.
For standard flow switches, the relay operates as stated below. For nonstandard units, the operation is
described in SPECIAL INSTRUCTIONS (SECTION 6).
A. Low Flow Switch The relay is energized (N.O. contact is closed) and the LED is green
when the flow rate is
above the trip level. Therefore, the alarm condition (relay de-energizes)
occurs when the flow rate drops below the trip level or there is a loss of power to the sensor
(N.O. contact is open and LED color becomes red).
B. High Flow Switch The relay operation is exactly as described above. When used as a high
flow switch, the alarm condition is considered to be when the relay is energized (N.O. contact
is closed and LED color becomes green).
3.2 GENERAL INFORMATION
The Rheotherm instrument is compensated for a wide range of both ambient and flowing media
temperatures. However, abrupt changes in the temperature of the flowing material can cause the
instrument to read the flow rate improperly, which could lead to an inappropriate tripping of the relay
or a delay in reading loss of flow. A proper reading is obtained only when the transducer is in thermal
equilibrium with the material. Typically, a 20°F abrupt change in temperature may require 40 seconds
to stabilize.
In general, the heater used in the transducer does not develop enough power to cause damage to the
system in the absence of flow. This includes those used in liquids even if the line becomes empty and
filled with air. Special cases will be discussed in the section entitled SPECIAL INSTRUCTIONS
(SECTION 6).